Botulinum neurotoxin A (BoNT/A) is one of seven botulinum neurotoxins (designated BoNT/A-G) produced by the anaerobic bacteria strain Clostridium botulinum (Schiavo G et al., Physiol. Rev. 80:717-766, 2000). BoNTs block neurotransmitter release by cleaving members of the membrane fusion machinery composed of SNAP-25, vamp-2/synaptobrevin (Syb), and syntaxin (Jahn R and Niemann H, Ann. NY Acad. Sci. 733:245-255, 1994; Schiavo G et al., supra, 2000). Cleavage of these proteins in motor nerve terminals blocks acetylcholine release at the neuromuscular junction (NMJ) which causes paralysis and may lead to death due to respiratory failure (Schiavo G. et al., supra, 2000; Simpson L L, Ann. Rev. Pharmacol. Toxicol. 44:167-193, 2004). Due to extreme potency and lethality as well as ease of use and transport, BoNTs are considered one of the six most dangerous potential bioterrorism threats (designated by Center for Disease Control of United States) (Amon S S et al., JAMA 285:1059-1070, 2001). According to the American Medical Society, as little as one gram of crystalline toxin is sufficient to kill one million people.
Currently, the standard test for BoNTs is the mouse bioassay available at the Centers for Disease Control and Prevention (CDC) and select laboratories across the country. The test involves treating mice with clinical samples suspected of carrying one of the BoNTs. The mice are immunized against the various BoNTs, and only those mice immunized against the specific BoNT present in the sample will survive. Although the test is sensitive in that it can detect as little as 0.03 ng of a BoNT, it is expensive and takes days to complete. On the treatment side, equine antitoxin containing antibodies against a BoNT is the therapy of choice and its effectiveness depends on timely treatment. This treatment, however, has all the disadvantages of a horse serum product such as the risks of anaphylaxis and serum sickness. Many times, treatment begins before botulism is confirmed as the diagnostic test takes days which is too long to wait for effective treatment. Therefore, there is a need in the art for alternative detection and treatment strategies.